Method for cold stable biojet fuel

Abstract

Plant or animal oils are processed to produce a fuel that operates at very cold temperatures and is suitable as an aviation turbine fuel, a diesel fuel, a fuel blendstock, or any fuel having a low cloud point, pour point or freeze point. The process is based on the cracking of plant or animal oils or their associated esters, known as biodiesel, to generate lighter chemical compounds that have substantially lower cloud, pour, and/or freeze points than the original oil or biodiesel. Cracked oil is processed using separation steps together with analysis to collect fractions with desired low temperature properties by removing undesirable compounds that do not possess the desired temperature properties.

The invention claimed is: 
     
       1. A method for producing a fuel composition that is stable at low temperatures, wherein the fuel composition is derived from biomass comprising the steps of:
 (a) adding an oil or oil ester, wherein the oil or oil ester is obtained from plant, biological lipid, or animal biomass, into a reactor vessel; 
 (b) heating the oil or oil ester in the reactor vessel in an absence of externally added hydrogen to a temperature ranging from about 100° C. to about 600° C. at a pressure ranging from about vacuum conditions to about 3000 psia for a time sufficient to crack the oil or oil ester; 
 (c) removing undesired material, unreacted oil or oil ester, and light ends from the cracked oil or oil ester; 
 (d) separating the cracked oil or oil ester and collecting fractions of the cracked oil or oil ester including at least one fraction selected from the group consisting of C 4  to C 16  alkanes, C 4  to C 16  alkenes, C 4  to C 16  aromatics, C 4  to C 16  cycloparaffins, C 4  to C 16  alcohols, C 2  to C 16  fatty acids, C 2  to C 16  fatty acid methyl esters and combinations thereof; and 
 (e) combining the collected fractions of cracked oil or oil ester to produce a fuel composition having a cloud point less than −10° C. 
 
     
     
       2. The method of  claim 1 , wherein the cloud point of the fuel composition is less than −20° C. 
     
     
       3. The method of  claim 2 , wherein the cloud point of the fuel composition is less than −30° C. 
     
     
       4. The method of  claim 1 , wherein the pour point of the fuel composition is less than −40° C. 
     
     
       5. The method of  claim 1 , wherein the oil or oil ester is a crop oil selected from a group consisting of soybean oil, canola oil, palm oil, sunflower oil, corn oil, flax seed oil, jatropha oil, cottonseed oil, safflower oil, crambe oil, evening primrose oil, sesame oil, rapeseed oil, olive oil, coconut oil, camelina, and combinations thereof. 
     
     
       6. The method of  claim 1 , wherein the oil or oil ester is a biodiesel generated through transesterification of crop oil, biological lipid, animal fat oil, or any combination or mixture thereof. 
     
     
       7. The method of  claim 1 , wherein the temperature in the reactor vessel is between 300° C. and 500° C. 
     
     
       8. The method of  claim 1 , wherein the oil or oil ester is heated in the reactor vessel for a time ranging from one to 180 minutes. 
     
     
       9. The method of  claim 1 , wherein heating in the reactor vessel occurs in a gaseous environment wherein the gaseous environment includes at least one of an inert gas, nitrogen, water vapor, or a mixture of vapor-phase organic chemicals. 
     
     
       10. The method of  claim 1 , wherein a catalyst is added to the reactor vessel. 
     
     
       11. The method of  claim 10 , wherein the catalyst improves yield of collected fractions;
 decreases formation of undesired material, unreacted oil or light ends; or increases cracking efficiency. 
 
     
     
       12. The method of  claim 1 , wherein the reactor vessel is of a type selected from a group consisting of batch, continuous flow through, flow through packed bed, and fluidized bed. 
     
     
       13. The method of  claim 1 , wherein separating and collecting fractions of the cracked oil or oil ester includes chemical analysis. 
     
     
       14. The method of  claim 1 , wherein the oil or oil ester fractions separated and collected include at least one of C 4  to C 12  alkanes, alkenes, aromatics, cycloparaffins, or alcohols; C 2  to C 12  fatty acids; and C 2  to C 12  fatty acid methyl esters. 
     
     
       15. The method of  claim 14 , wherein the oil or oil ester fractions separated and collected include at least one of C 4  to C 8  alkanes, alkenes, aromatics, cycloparaffins, or alcohols; C 2  to C 8  fatty acids; and C 2  to C 8  fatty acid methyl esters. 
     
     
       16. The method of  claim 1 , further comprising blending the fuel composition with petroleum-based turbine fuel selected from a group consisting of Jet A, JP-4, JP-5, JP-8 and combinations thereof in ratios ranging from greater than 0% to less than 100% petroleum-based turbine fuel to produce a turbine fuel blendstock. 
     
     
       17. The method of  claim 1 , wherein the fuel composition has acceptable combustion properties and cold temperature properties for a diesel engine and is equivalent to a standard diesel #1 transportation fuel. 
     
     
       18. The method of  claim 1 , further comprising blending the fuel composition with standard diesel #1, diesel #2 or a combination thereof petroleum-based diesel fuel in ratios ranging from greater than 0% to less than 100% petroleum-based diesel fuel to produce a diesel engine fuel blendstock. 
     
     
       19. A fuel composition having a low temperature cloud point, formed by a process in which an oil or oil ester derived from biomass is cracked in a reactor vessel in an absence of externally added hydrogen; processed to remove residual material, unreacted oil and light ends; and separated to collect fuel fractions, which when combined, have a cloud point less than −10° C. 
     
     
       20. A fuel composition comprising:
 (a) a biofuel composition derived solely from plant or animal biomass by cracking the plant or animal biomass in an absence of externally added hydrogen and having a cloud point of less than −10° C., and including:
 (1) a hydrocarbon component consisting essentially of C 4  to C 16  alkanes, alkenes, aromatics, cycloparaffins, and alcohols; and 
 (2) a fatty acid component consisting essentially of at least one of C 2  to C 16  fatty acids and C 2  to C 16  fatty acid methyl esters. 
 
 
     
     
       21. The fuel composition of  claim 20 , wherein the fuel composition has a cloud point of less than −20° C. 
     
     
       22. The fuel composition of  claim 20 , wherein the fuel composition has a cloud point of less than −30° C. 
     
     
       23. The fuel composition of  claim 20 , wherein the fuel composition has a pour point of less than −40° C. 
     
     
       24. The fuel composition of  claim 20 , wherein the hydrocarbon component and the fatty acid component together constitute at least 50% by volume of known identified chemical compounds in the fuel composition. 
     
     
       25. The fuel composition of  claim 20 , further comprising:
 (b) petroleum-based turbine fuel selected from a group consisting of Jet A, JP-4, JP-5, JP-8 and combinations thereof in ratios ranging from greater than 0% to less than 100% petroleum-based turbine fuel; 
 wherein the fuel composition is a turbine fuel blendstock. 
 
     
     
       26. The fuel composition of  claim 20 , further comprising:
 (b) standard diesel #1, diesel #2 or a combination thereof petroleum-based diesel fuel in ratios ranging from greater than 5% to less than 95% petroleum-based diesel fuel; 
 wherein the fuel composition is a diesel engine fuel blendstock. 
 
     
     
       27. The method of  claim 1 , wherein the oil or oil ester is heated in the reactor vessel in the absence of a catalyst. 
     
     
       28. The method of  claim 1 , wherein the fuel composition contains between about 15% by weight and about 25% by weight C 7  to C 18  alkanes. 
     
     
       29. The method of  claim 28 , wherein the fuel composition contains between about 44% by weight and about 54% by weight C 4  to C 22  saturated fatty acid methyl esters. 
     
     
       30. The method of  claim 29 , wherein the ratio of C 7  to C 18  alkanes to C 4  to C 22  saturated fatty acid methyl esters is between about 2:7 and about 4:7. 
     
     
       31. The method of  claim 28 , wherein the fuel composition contains between about 29% by weight and about 60% by weight C 4  to C 12  saturated fatty acids. 
     
     
       32. The method of  claim 31 , wherein the ratio of C 7  to C 18  alkanes to C 4  to C 12  saturated fatty acids is between about 1:4 and about 6:7.